Extract values from JSON, YAML, TOML, CSV, XML, or PSD1 files using path expressions like 'users[*].email', returning matches as JSON.
Extract values from a json/yaml/toml/csv/xml/psd1 file with a path expression such as 'servers[0].name', 'users[].email' or '.port'. Returns JSON (a list of matches).
| Name | Required | Description | Default |
|---|---|---|---|
| path | Yes | ||
| query | Yes | ||
| format | No |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v0.2.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds the return shape ('Returns JSON, a list of matches'), which is genuinely useful, but says nothing about behavior on zero matches, malformed queries, or unsupported file types.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two sentences, front-loaded with the core action and followed by concrete, non-redundant syntax examples. No filler, though the overloaded word 'path' in both the file-argument and expression-argument senses slightly muddies the structure.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
An output schema exists, so return-value detail is largely unnecessary and the description's one-line note suffices. However, with three parameters at 0% schema coverage and an unlocked 'format' option, the definition leaves an agent guessing about at least one argument's semantics and about failure behavior.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 0%, so the description carries the burden. It effectively explains the 'query' parameter via path-expression examples, but leaves the distinction between 'path' (the file) and "path expression" ambiguous, and never mentions the optional 'format' parameter — presumably auto-detected from extension, but the agent must infer that.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb ('Extract values') plus the resource (structured files) and enumerates supported formats, so an agent can distinguish it from generic text search or conversion tools. It stops short of naming which sibling to use instead (e.g. convert_data for format conversion, grep for plain text).
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The example query expressions implicitly show the intended use case (drilling into structured documents), but there is no explicit statement of when to reach for this over read_text_file, grep, or convert_data. No exclusions or prerequisites are given.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.